352 PHYSICS. 



solidifying ; so that, after rupture of the shell, the congelation took 

 place. The curious appearances of the jets are figured in the memoir. 

 {Bib. Univ., 1880, III, iii, 531; J. Phys., April, 1881, x, 181.) 



The paradoxical experiment of " hot ice" described by Carnellcy has 

 been repeated by many observers in various ways. Lodge has discussed 

 the matter on general principles, conceding that the ice itself may be 

 hot, a proposition in which he thinks there is nothing contradictory to 

 our present knowledge of the properties of matter. Carnelley himself 

 has published an additional paper, with figures, in which he says: •'! 

 have had thin plates of ice attached by their edge at right angles to the 

 stem of a paper-scale theraiometer for a considerable time without being 

 detached or melting, notwithstanding the temperature was so high that 

 the paper scale at that portion of the stem to which the ice clung was 

 charred. In another instance I have had a thin circular piece of ice 

 attached to the otherwise bare bulb of the thermometer, and though this 

 piece was very thin, and no more than about 2 millimeters in diameter, 

 it took fully one minute or more to volatilize, notwithstanding the ther- 

 mometer indicated a mean temperature of 70° C, and the surrounding 

 tube was very hot. If the ice were not capable of being heated above 

 its melting point, a ijiece as small as that referred to would, I think, 

 under these circumstances have fused or volatilized almost instantane- 

 ously." Herschel has contrived a remarkably simple apparatus for show- 

 ing the phenomena. A 30-ounce flask of heavy glass was tightly closed 

 by a rubber cork through which passed a tube three-eighths inch bore 

 and 2 feet long, bent into the shape of an S, and the extremity drawn 

 into a nearly cai^illary neck. This neck was connected hy a rubber 

 tube with with a similar flask, to which was attached an exhaust pump, 

 and which was immersed in cold water. Fifteen ounces of water were 

 then boiled in the flask thus exhausted, and when only 3 ounces re- 

 mained the small end of the tube was sealed. The U-part of the tube 

 was put in a freezing mixture till a sleeve of ice was formed eight inches 

 long. Then the flask was similarly treated, and the tube was heated 

 first in a water-bath, then by the naked flame. He says : "The whole 

 tube was heated violently, without for some time appearing to have the 

 least effect upon the white crust v»athin, notwithstanding the tube was 

 too hot to be touched." De la Eiviere and Van Hasselt have repeated 

 the experiments carefully, with the aid of accurate thermometers. They 

 find the ice itself is generally at — 7° C, though when the heating is verj- 

 strong it may rise to 0°. They found that the result could easily be 

 obtained with naphthalene. Hannay has constructed an apparatus, 

 from ordinary laboratory materials, with which he has examined the ])he- 

 uomena very critically. He performed the crucial experiment of ])lacing 

 a bulb containing frozen water and open to the air, inside the mass of 

 ice within the exhausted tube. The ice within the bulb did not melt 

 even when the tube round the ice in vacuo was raised to the i)oint of 

 softening. The results of McLeod, Lothar Meyer, Boutlerow, Peters- 



